Shutter mechanism



Feb. l, 1966 E. s. MCKEE ETAL.

SHUTTER MECHANISM Filed Sept. 6, 1965 United States Patent O 3,232,690SHUTTER MECHANISM Edward S. McKee, Gerald L. Jenkins, and David L.Babcock, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester,N.Y., a corporation of New Jersey Filed Sept. 6, 1963, Ser. No. 307,14312 Claims. (Cl. 352-209) The present invention relates to -a shuttermechanism for a motion picture projector and more particularly to ashutter mechanism for increasing the number of shutter blades forflickerless slow speed projection.

Motion picture projectors are ynormally provided with a multi-bladedshutter for interrupting the light beam projecting an individual frameof the filmstrip onto a screen. At normal projection speeds, amulti-bladed shutter is desirable so as to obtain maximum uniformbrightness of the projected picture on the observing screen and toeliminate light flicker. However, because the film `advancing mechanismis generally driven by the shutter shaft, when the speed of theprojector is reduced for slow motion effects, there is a correspondingreduction in the rotational speed of the shutter resulting in lightfiicker. Light fiickeris directly related to the number of light in"-terruptions by the shutter blades in a given period of time andgenerally occurs when the number of interruptions is less than fiftyinterruptions per second. Thus, if a motion picture projector isoperated for slow motion effects with an accompanying reduction inshutter interruptions, light flicker can be eliminated by increasing thenumber of Vshutter blades to obtain fifty interruptions per second.

An object of thisinvention is to provide a shutter mechanism which willautomatically increaserthe number of light interruptions when the speedof the projector is reduced for slow motion; and, conversely, to lreducethe number of shutter blades when the speed of the projector is changedfrom slow motion to normal speed.

A further object of this invention is to provide a shutter mechanismwhich is coupled with the film advance mechanism, such that when it isdesired to reduce the projector speed, the number of blades of theshutter mechanism automatically increase.

Another objectV of this invention is to provide a shutter mechanismwhich is coupled to a selective shifting device which automaticallychanges the number of shutter blades when the shifting device is movedfrom normal to slow motion operation and vice-versa.

Other objects Iand a fuller understanding of the invention can be had byreferring to the following description and claims taken in conjunctionwithV the drawings in which:

FIG. 1 is a fragmentaryV perspective view of a motion picture projectorincorporating my invention;

y FIG. 2 is a side view, in cross-section, showing the shutter mechanismin the slow speed position; V

FIG. 3 is a View, partially inY section, of the shutter mechanism takenalong the line 3-3 of FIG. 2;

FIG. 4 is a side View, in cross-section, showing the shutter mechanismin the normal speed position;

FIG. 4a is an exploded perspective view of the actuator for the shuttermechanism shown in FIGS. 2 and 4.

FIG. 5 is a View, partiallyin section, of the shutter mechanism takenalong the line 5 5 of FIG. 4;

3,232,690 Patented Feb. 1, 1966 ICC FIG. V6 is a side view, incross-section, of -another embodiment of the shutter mechanism which isshown in the normal speed position; and

FIG. 7 is a side view, in cross-section, showing the shutter mechanismof FIG. 6 in the slow speed position.

To better understand the novel shutter mechanism described hereinbelow,a brief summary will be helpful. A first shutter disk having a pinprojecting from one of its faces is fixed to the rotating shutter shaftof the motion picture projector. The shutter disk has one or moreshutter blades projecting radially therefrom wihch sweep through acircular path such that the individual blades of the shutter interruptthe projection light beam emanating from a light source. A secondshutter disk which is mounted for rotation on the shutter shaft iscoupled to the first shutter disk by means of a pin-in-slot connection.The second shutter disk has substantially the same number of blades asthe first shutter disk so that when the blades of the two disks arealigned with each otherthey interrupt the light beam at the same moment.A first driven pulley mounted for rotation on the shutter shaft isconnected to a drive shaft by a drive belt. The pulley is axiallymovable alongkthe shutter shaft, and is normally coupled to drive the.first shutter disk at a given speed. A second driven pulley which ismounted on the shutter shaft for rotation `and axial movement therealongis also coupled to the drive shaft to be driven therefrom.

The first and second driven pulleys are rotatable in.- dependently ofeach other, but are coupled so that they can be moved together betweentwo positions along the shaft. When the pulleys are in the first of saidtwo positions, the first driven pulley transmits power from the driveshaft to the shutter shaft and thence to the first disk which shutterdisk in turn carries the second shutter disk with it. When the pulleysare shifted to the second of said two positions, the first driven pulleyis uncoupled from the first shutter disk and the second driven pulley iscoupled to the second shutter disk to drive the same. Because thedriving force for the shutter shaft is now exerted through the secondshutter disk, the second shutter disk will rotate relative to the firstshutter disk until the opposite end of the arcuate slot in said seconddisk picks up the pin on the first shutter disk to drive said firstshutter disk and the shutter shaft to which it is fixed. The relativemovement between the two shutter disks, resulting from the pin-in-slotconnection between the two, |arcuately displaces the blades of the firstshutter disk relative to the blades of the second shutter disk, therebyincreasing the number of blades for interrupting the light beam. Thus,if the second driven pulley has a diameter which is greater than thediameter of the first driven pulley, the speed of the pulldown mechanismwill be reduced for slow motion effects and the number of bladescomprising the shutter can be increased sufficiently to interrupt thelight beam approximately fifty times per second to eliminate lightflicker.

Referring more particularly to FIG. 1 of the drawings, our improvedshutter mechanism is disclosed in association with a motion pictureprojector. The projector housing 10 encloses an optical systemcomprising a reflector type lamp 12, gate ffl and projecting lens 16 forprojecting individual frames of a motion picture filmstrip 18 onto ascreen (not shown). A reversible drive motor 20, having a pair of drivepulleys 22 and 24, respectively, spaced on its drive shaft 26, ismounted on the baseof housing 1li. A Vshutter shaft 28, journaled withinhousing 10',

and above drive shaft 26, has a pair of spaced driven pulleys 30 and 32,rotatably mounted thereon and su-bstantially in alignment with therespective drive pulleys 22 and 24. Pulley belts 34 and 36,respectively, couple driven pulleys 3l) and 32 to their respective drivepulleys 22 and 24 on drive shaft 26. Projector speed control lever 38,-pivotally mounted on housing 10, selectively determines which of thedriven pulleys Will be coupled in driving relationship with driveshaft-26. A pair of three bladed shutter disks 40 .and 42, havingaligned shutter blades'41 and 43, res-pectively, are mounted on shuttershaft 28 to interrupt the light passing through the optical system.Pulldown mechanism 44 is also operatively coupled'to shutter shaft 28for intermittently moving lmstrip'18 through gate 14 past the opticalsystem. By the mechanism more `particularly described hereinbelow, the pair of shutter disks v40 and 42 can be displaced an arcuate distancerelative to each other when the control lever 38 is moved from a normalforward position to a slow speed position.

As best shown in FIGS. 4`and 4a, a circular collar 46 is'fastened byscrew 45 to shutter shaft 28 adjacent one end thereof. Two vor morelongitudinal grooves 47 are formed in the marginal portion `adjacent theinner periphery of collar 46. Apulley actuator member 48, of the formbest shown in FIG. 4, having the same number of legs S as the collar 46has grooves 47, tits over the `end of shutter shaft 28 with its'legs 50slidably engaging 'grooves 47 and extending completely through collar46. 'Lever 38engagesactuator member 48 and is adapted to be rotatedabout its pivot point 52 to move actuator member 48`lengthwise ofshaft28.

Driven pulley 30, carried on circular slide bearing 54, is revolvaiblymounted for rotation relative to shaft 28. A ring-shaped washer 56separates the ends of legs 50 from the end face of bearing 54. Pins 58projecting from the inner face 60 of collar 46 towards pulley 30 and ata given distance fromthe axis of shutter shaft 28, moves in a givencircle of rotation. A similar pin 62 on the face of driven pulley 30projects towards collar 46 'and moves in the same :given circle ofrotation as does pin 58.

Similarly, driven pulley 32, carried on circular slide bearing "64, isrevolvably mounted for rotation relative to shaft 28. Driven pulley 32has a diameter which is greater than the diameter of pulley 301 so thatif both pulleys .30 and 32 are driven by equal diameter drive ypulleys22 and 24, respectively, the peripheral speed of pulley 32 will be lessthan the 'peripheral speed of pulley 30. Ring-shaped washer 66 separatespulleys 38 and 32 so that they can rotate independently of each other. Acentrally vdisposed circular cavity 68 is formed in face 70 of pulley32. A ring-shaped washer 72 which can slide 'along shaft 28 is locatedwithin cavity 68, with face 74 thereof slidably engaging the end face ofbearing 64. A ,'pin 73 'projects from face 70 of pulley 32 and is'located at a radius from the center axis of shaft 28 which is greaterthan the radius of cavity 68.

A circular hub member 76, partially extending into cavity 468, isfastened to shaft 28 b -y set screw 78. A

'coiled conical compression spring '82, whose lbase is positioned on theface 80 of hub member 76, slidably `engages face 84 of washer 72 andurges pulleys 30 andv 32 towards collar 46. A circular ringy ymember 86is revolvably'carried on recessed shoulder 88 formed in 'hub member 76.Shutter disk 40 is fastened. to ring member 86 by pins 90. A pin 92projects from ring member 86 towards -pin 73 and is positioned on member86 at a radius from the center axis of shaft 28 which `is the ysame aspin 73.

Shutter disk 42 is fastened to shaft 28 for rotation therewith, andmoves in a plane of rotation which is parallel to the plane of rotationof disk 40. A pin 94 fastened to disk'42 projects away Yfrom face 96thereof and is slidably accepted in arcuate slot 98 of disk 40. CoiledAtension spring 100 extending between pin 102 on disk 42 'and pin 104 ondisk 40 biases pin 94 towards end 106 of slot 98. Thus, when shaft 28 isrotated in the forward (F) direction, as shown in FIG. 5, pin 94 on disk42 carries disk 40 therewith. But when shaft 28 drives disk 42 in thereverse (R) direction, the tension force exerted by spring is suflicientto retain disks 40 and 42 in the same position as they were when drivenin the forward (F) direction.

In operation, control member 38 is preferably `first positioned in thenormal speed position, as best shown in FIG. 4, wherein member 38 exertslittle or no force on actuator member 48. Compression spring 82 seatedon hub 76 exerts a biasing force on washer 72 to displace slide bearings54 and 64, washers 56, 66, and 72, and actuator member 48 longitudinallyon shutter shaft 28 until washer 56 engages 'face 60 of collar 46.Driven pulleys 30 and 32 carried by `bearings'54 and 64, are alsodisplaced such that the path of rotation of pin 62 of pulley 30intercepts the path of rotation of pin 58 of collar 46, whereas, pin 73of pulley 32 is displaced from the path of rotation of pin 92 of ringmember 86.

When power is applied to drive motor 20 by means of a separate switch(not shown) motor 20 is energized and will rotate shaft 26 and itsaccompanying drive pulleys 24 and 26. Belts 34 and 36 will rotate drivenpulleys 30 and `32, respectively. Becausepin 73 is removed from the pathof pin 92 driven pulley 32 will not be coupled to the shutter shaft todrivethe samegbut will rotate relative thereto. Driven pulley 30,however, will rotate on shaft 28 until its pin 62 picks uppin 5 8 ofcollar 46, and places driven pulley 30 in driving engagement with collar46. Collar 46, secured to shaft 28, will rotate shaft 28 in a clockwisedirection as shown in FIG. 5. Shutter disk 42 will thus also be rotatedin a clockwise direction, and, as pin 94 on disk 42 co-operates withslot 98 of disk 40, shutter disk 40 will be carried along with disk 42.Shutter blades 41 and 43 of shutter disks 40 and 42 will be in alignmentand interrupt the projector light beam simultaneously.

For the reverse operation of .the projector, at normal speed, thedirection of rotation of electric drive motor 20 is reversed andaccordingly, the direction 0f rotation of drive pulley 22, belt 34 anddriven pulley 30, collar 46, driven shaft 28 a-nd disk 42 will bereversed. As best shown in FIG. 5, pin 94 on disk 42 would thus tend tomove in slot 98 towards end 108 in order to drivingly couple disk 40 forrotation. However, tension spring 100 exerts a force sufficient toretain the end 106 of slot 98 in engagement with pin 94.

If now, the slow speed operation is desired, control lever 38 is pivotedcounterclockwise abou-t its point 52 from the normal speed position tothe slow speed posi# tion as shown in FIG. 2. When control lever 38 isso moved, legs 50 of actuator member 48 bear against Washer 56 and byvirtue of this engagement will move washers 56, 66, and 72, bearings 54and 64, and their respective driven pulleys 30' and 32, 'along shaft 28towards hub member 76. The pivotal force exerted on lever 38 issuflicient to compress spring 82. A detent (not shown) will retain lever38 in the slow speed position. In this position pin 62 of pulley 30 islongitudinally displaced and Vbecomes disengaged from pin 58 of collar46, whereas the` path of rotation of pin 73 of pulley 32 is now movedinto the path of rotation of pin 92 of ring member 86. Pin 73 picks uppin 92 and carries it along with it so that ring Amember 86 and hencedisk 40 are being driven by pulley 32. Because ofthe inertia forces ofthe pulldown mechanism 44 (see FIG. 1), shaft 2S and hub 76, disk 40will slidably rotate on hubmember 76,until pin 73 engages pin 92, afterwhich disk 40 is in driving engagement with motor 20.

As best shown in FIG. 3, when disk 40 is driven, it will rotate in aclockwise direction relative to disk 42 until pin 94 reaches the end 108of slot 98 in disk 40, after which disk 42 will be carried along with'disk "4.0`

Thus, 'as is shown in FIGS. 1, 2, and 3, disk 40 is displaced arcuatelyrelative to disk 42, by a distance determined by the length of slot 98.In this position, wherein pulley 32 is driving disk 40 at a slowerspeed, blades 41 of disk 48 are displaced relative to blades 43 of disk42 to provide a six bladed shutter for interrupting the light beam. Thedrive for the pulldown mechanism 44 is now: drive motor 20, drive pulley24, belt 36, driven pulley 32, pin 73, pin 92, hub member 76, disk 40,pin 94, disk 42 and shaft 28. Driven pulley 30, which is constantlybeing driven by belt,34, freely rotates on shaft 28.

Another embodiment of the shutter mechanism is illustrated in FIGS. 6and 7, in which driven pulleys 130 and 132 are coupled together formovement along the axis of shutter shaft 128 by a cup shaped couplingmember 134. Pulley 130, carried on bearing 136, is revolvably mounted anshutter shaft 128. Bearing 136 includes a ring shaped flange 138 at oneof its ends. A ring-shaped washer 139 is revolvably mounted on the outersurface of bearing 136'and is positioned intermediate ange 138 and endface 140 of pulley 130.

A collar 146 is fastened to shaft 128 by screw 147 and has a pin 158projecting from its inner face 160 towards pulley 130. Pin 158 ispositioned at a given distance from the center axis of shutter shaft 128and moves in la given circle of rotation. A similar pin 162 on the faceof driven pulley 130 prejects towards collar 146 and moves in the samegiven circle of rotation as does pin 158.

Similarly, driven pulley 132, carried on cylindrical slide bearing 164,is mounted for rotation relative to shaft 128. Driven pulley 132 has adiameter which is greater than the diameter of driven pulley 130 so thatthe peripheral speed of pulley 132 will be less than the peripheralspeed of pulley 130` when the pulleys are driven by equal dia-meterdrive pulleys connected to thedrive shaft (not shown). Pulley 132includes a pair of centrally disposed circular cavities 158 and 151,respectively, which are formed in the opposite faces of pulley 132. Apin 173 projects outwardly from the face of pulley 132 adjacent tocavity 151. Cavity 150 has a recessed groove portion 152 adjacent itsbottom, which groove portion has a diameter larger than the cavity, foraccepting an overcenter toggle spring 154 which is movable between twopositions. The opposite ends of toggle spring 154 engage the walls ofgroove portion 152 to seat the toggle spring within cavity 158. Anenlarged aperture 155 in the center oftoggle spring 154 permits thetoggle spring to move between its two positions with- 6 position to theother, and further retains the pulleys in the position they are movedto.

A circular hub member 178 is fastened to shaft 128 by set screw 179. Acylindrical ring member 186 is revolvably carried on shoulder 188 o-fhub member 178 for rotation relative to shaft 128. A shutter disk 240'is fastened by means of a rivet 198 to ring member 186 for rotationtherewith relative to shaft 128. A pin 192 fastened to ring member 186projects outwardly from its surface and towards pin 173. Pins 173 and192 are positioned on pulley 132 and ring member 186, respectively, atthe same radius from the center axis of shaft 128. Shutter disk 242 isfastened to shaft K128 for rotation therewith and moves in a plane `ofrotation which is parallel to the plane of rotation on disk 240.

A pin 194, fastened to disk 242, projects away from lthe face 196thereof and is slidablyV accepted in a slot 198 on disk 240. Coiledtension spring 208 extending between pin 202 on disk 242, and pin 2114on disk 248, couples shutter disks 248 and 242 together in a mannersimilar to that previously disclosed. Except for the above diiference,this embodiment is substantially like that previously disclosed inconjunction with the FIGS. l-5.

In operation, control member 166 is preferably first positioned in thenormal speed position as best shown v in FIG. 6, wherein the margin-alportions o-f the aperture yout binding on the surface of shaft 128. Apair of spaced rings 156 and 157 are fastened to shaft 128, and arepositioned thereon to engage the opposite marginal surfaces adjacentaperture 155 for the purpose of limiting tlie displacement of thecentral portion of toggle spring 154.

Coupling member 134, which has an aperture 135 centrally located thereinof a diameter greater than the diameter of bearing 136 but less than thediameter of ange 138, is fastened to pulley 132 and vsubstantiallyencloses the opening of cavity 150i. The marginal portions of coupling134 adjacent aperture 135 is positioned intermediate ange 138 of bearing136 and washer 139. Thus, pulley 132 is coupled to pulley 130 such thatany movement of pulley 132 along the axis of shaft 128 will move pulley138 a corresponding distance.

Pulley 132 includes a groove 1155 for-med in the circular outer surfacethereof. A roller 161, revolvalbly mounted on a pin 163, fastened tlomovable control lever 166, is positioned to engage the Walls orf groove165. Control lever 166 is swingable between two positions, and, becauseof the co-operation of roller 161 with groove 165, will move pulleys 130and 132 along shaft 128. Toggle spring 154 co-operating with rings 156and 157 on shaft 128 quickly moves pulleys 130 and 132 from one 155 ofthe toggle spring 154- engalge was-her 157 on driven shaft 128, and thetoggle spring urges pulley 132 and pulley tolwarrls collar 146. In thisposit-ion, puliey 138 is driven by drive belt 131 with pin 152 rotatingin the path of pin 158. Clollar 146 will rotate shaft 128, and shutterdisk 242 in a manner similar to that disclosed with reference to FIGS. 4and 5. By virtue of the pin-in-sllot connection, shutter disk 240 willbe driven by shutter disk 242 with their blades in alignment to providea three blade shutter in accordance with the embodiment shown in FIGS.l-5. If now, the slow speed operation is desired, contro-l lever 166will be moved to tbe right and viewed in FIG. 7. In moving control lever166, roller 166 will engage the opposite wall of groove 165 in pulley132. The force exerted by lever 166 wilil move driven pulleys 131D and132 towards shutter blades 241) and 242, which movement will displacetoggle spring 154 from its position as shown in FIG. 6 to its plositionas shown in FIG. 7. In so moving driven pulley 130, pin 152 carriedtherebyA is laterallly displaced and becomes disengaged from pin 158 ofcollar 146; while at the same time, the pin 173 01f pulley 132 is nolwmoved into the path of rotation4 of pin 192 of ringr member 185. Pin 173picks utp pin 192 and carries it allong so that ring member 185 andhence disk 248' will be driven by pulley 132. Now, als the drive is nowconnected to disk 240, disk 240 wil-l rotate relative to disk 242 untilthe end of the slot 198 engages pin 194 on disk 242 whereupon the twodislss will rotate together. 'lllris relative rotation of the two disksprovided by the pin and slot connection results in the two disks forminga shutter having twice the number of blades as when they are inalignment, as d-isclosed in connection with the embodiment sho-Wn inFIGS. l-S. As pulley 132 has a larger diameter, shutter shaft 128 willrotate at the desired slower speed for slow motion effect. Because theshutters 241i and 242 have been displace-d relative to each other, theirshutter blades (not shown) wili be arcuately displaced relative to eachother to form a shutter providing a sufficient number of interruptionsof the light beam to prevent light flicker.

While the embodiments of the invention shown and described herein havebeen particularly described relative to a motion picture projector, itis to be understood that the inventive idea can be carried out in anyother motion picture apparatus in which a Variable blade shutter isdesired.

Tlhe inventionhas been described in detail with particular reference toembodiments thereof, but it will be understood that variations andmodifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims;

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as tlollows:

li. In a motion picture projector having drive means selectively capableof at least two different speeds of operation and a shutter driven bysaid drive means, said shutter comprising at least two coaxial diskseach provided with alike number of blades and rotatably displaceaiblerelative to one another between a first condition, wherein. the bladesof said two dislcs are in alignment with one another to, in effect,utilize half the total number of blades, and a second condition, whereinthe blades of said two disks are displaced relative to each other toutilize the total number of blades, the improvement comprising:

(a) a lost motion drive connection between said disks for selectivelydriving either disk by the other and which provides a relativerotational displacement of said disks between said finst condition whenone of said disks is driven by the other and said second condition whensaid other disk is driven by said one disk, and

(b) means for selectively connecting said disks to sai-d driven means tobe rotated thereby in response to a vselected change in speed ofoperation off said drive means.

2. In a motion picture projector having a drive shaft,

a driven shaft normally operatively coupled to said drive shalt to bedriven thereby, a first shutter secured to said driven shaft .forrotational movement therewith and including at least one radial blade, asecond shutter rotatably mounted on said driven shaft coaxially withsaid irst shutter and including at least one radial blade, theimprovement comprising:

(a) a selective drive coupling between said first and second shuttersmovable between a norrnlal first condition, in which said first andsecond shutters are rotated together with their blades in overlappingrelation, and a second condition, in which said first land secondshutters are rotated together after their blades have been arcuatelydisplaced, and

(b) means movable between a first position, wherein said driven shaft isnormally coupled to said drive shaft and-'said selective drive couplingis in said normal first condition, and a second position, wherein saiddriven shaft is uncoupled from said drive shaft and said selective drivecoupling is in said second condition.

3. The motion picture apparatus of claim 2 wherein said selective drivecoupling between said first shutter and said second shutter includes apin and slot connection for moving the blades of said first and secondshutters together in said normal first condition and for limiting thearcuate displacement of said yfirst shutter relative to said secondshutter in said second condition.

4. The motion picture projector of claim 3 wherein said drive shaft isreversible and said selective drive coupling Ibetween said first shutterand said second shutter includes a spring member urging said first andsecond shutters to move together with their blades in overlappingrelation Iwhen said drive shaft Imoves in the reverse direction and saidfirst shutter is coupled and driving said second shutter in the normalrst condition.

5. The motion picture projector of claim 4 wherein the force exerted bysaid spring member is less than the combined inertia and friction forceof said driven shaft `and said `first shutter, when said drive shaft iscoupled to said second shutter in said second condition 'whereby the1blade of said lfirst shutter is arcuately displaced relative to theblade of said second shutter.

t6. 4In a motion picture projector having an optical system, a drivenshaft, a first shutter secured to said -driven shaft for rotationalmovement therewith and having at least one radial blade adapted tointerrupt the light passing through said optical system, and meansoperatively coupled to said `driven shaft for intermittently advancing afilmstrip in a predetermined path past said optical system `when saidblade interrupts said optical system, the improvement comprising:

(a) a second shutter having at least one radial blade thereon forinterrupting the light passing through said optical system, said secondshutter rotatably mounted on said drive shaft coaxially relative to saidfirst shutter;

(b) a selective drive coupling between :said second shutter and said rstshutter movable between a first condition, wherein the Ablades of saidshutters are rotated together in overlappingV relation .and a secondcondition, wherein the blades of said lfirst and second shutters movetogether after being arcuately displaced relative to one another yforthe purpose of changing the number of light interruptions;

(c) a shiftable transmission means movable between two positions forselectivelyI operating said driven means at two different speeds;

(d) and means for moving said selective drive coupling to and from saidrst condition in response to movement of said shiftable transmission toand from the highe of said operating speeds.

7. In motion picture project-or having a projection light beam, a driveshaft, a driven shaft, a lfirst shutter secure-d to said driven shaftfor rotational movement therewith and having at least one radial bladeadapted to interrupt said light beam, and means operatively coupled tosaid driven shaft for intermittently a-dvancing a filmstrip in apredetermined 4path past said light beam when said blade interrupts saidlight beam, the improverncut comprising:

(a) a first shiftable transmission means normally coupling said drivenshaft to said drive shaft for rotating said -rst shutter;

(b) a second shutter, rotatably mounted on said driven shaft coaxiallyrelative to said first shutter, and having at least one radial bladethereon adapted to interrupt said light beam,

(c) a second shiftable transmis-sion means driven by said drive shaftand freely rotatable on said'driven shaft ywhen said .first shiftabletransmission means normally couples sai-d driven shaft to ysaid driveshaft:

(l) said -rst and second shiftable transmission means movablesimultaneously longitudinally Iof said driven shaft from a normalposition to a second position for uncoupling said rst transmission meansfrom said drive shaft and c oupling said second transmission means tosaid driven shaft, and

(d) 'actuating means for selectively moving said rst and secondshiftable transmission means from said normal position to said secondposition.

8. The apparatus of claim '7 `wherein said second transmission meansincludes means for reducing the speed of rotation of said driven shaftwhen said4 second transmislsion means is coupled to said drive shaft.

9. The apparatus of claim 7 wherein said second transmission meansincludes a peripheral groove and said actuating means includes a rollerrotatably mounted on a shiftable lever, with the axis of rotation ofsaid roller substantially perpendicular to the axis of rotation of saiddriven shaft, and whose surface is engageable with the side walls ofsaid groove for moving said second shiftable transmission between saidnormal position and said second position.

lil. The apparatus of claim 9 wherein said actuating means includes atoggle spring for rapidly moving said first and second transmissionmeans between said normal position and said second position, andretaining the same in the one lof said two positions into which it ismoved thereby.

3,23,69 9 10 11. The vapparatus of claim 7 wherein said second trans-References Cited bythe Examiner mission means includes a spring memberfor urging said UNITED STATES PATENTS second transmission means intosaid normal position.

said driven shaft for moving said transmission means from said normalposition to said second position. JULIA 'E' COINER Primary Examme"

1. IN A MOTION PICTURE PROJECTOR HAVING DRIVE MEANS SELECTIVELY CAPABLEOF AT LEAST TWO DIFFERENT SPEEDS OF OPERATION AND SHUTTER DRIVEN BY SAIDDRIVE MEANS, SAID SHUTTER COMPRISING AT LEAST TWO COAXIAL DISKS EACHPROVIDED WITH A LIKE NUMBER OF BLADES AND ROTATABLY DISPLACEABLERELATIVE TO ONE ANOTHER BETWEEN A FIRST CONDITION, WHEREIN THE BLADES OFSAID TWO DISKS ARE IN ALIGNMENT WITH ONE ANOTHER TO, IN EFFECT, UTILIZEHALF THE TOTAL NUMBER OF BALDES, AND A SECOND CONDITION, WHEREIN THEBLADES OF SAID TWO DISKS ARE DISPLACED RELATIVE TO EACH OTHER TO UTILIZETHE TOTAL NUMBER OF BLADES, THE IMPROVEMENT COMPRSING: (A) A LOST MOTIONDRIVE CONNECTION BETWEEN SAID DISKS FOR SELECTIVELY DRIVING EITHER DISKBY THE OTHER AND WHICH PROVIDES A RELATIVE ROTATIONAL DISPLACEMENT OFSAID DISKS BETWEEN SAID FIRST CONDITION WHEN ONE OF SAID DISKS IS DRIVENBY THE OTHER AND SAID SECOND CONDITION WHEN SAID OTHER DISK IS DRIVEN BYSAID ONE DISK, AND (B) MEANS FOR SELECTIVELY CONNECTING SAID DISKS TOSAID DRIVEN MEANS TO BE ROTATED THEREBY IN RESPONSE TO A SELECTED CHANGEIN SPEED OF OPERATION OF SAID DRIVE MEANS.